Nyström Andreas M, Wooley Karen L
Center for Materials Innovation, Department of Chemistry and Department of Radiology, Washington University in Saint Louis, Saint Louis, Missouri 63130-4899, USA.
Soft Matter. 2008 Mar 20;4(4):849-858. doi: 10.1039/b719314a.
Shell cross-linked knedel-like (SCK) block copolymer micellar nanoparticles were prepared from poly(acrylic acid-b-octadecyl acrylate-co-decyl acrylate) and studied as unique systems, having tunable core melting transition temperatures (Tm). Tm depression was accomplished by diluting octadecyl acrylate with the co-monomer decyl acrylate in the construction of the hydrophobic block segment of amphiphilic block copolymers of similar lengths and chemical compositions. Organization of those block copolymers into micelles and cross-linking throughout the shell then afforded a series of SCKs that exhibited core Tm values ranging from 3 to 40 °C. Confinement of the side-chain crystalline polymer chains within the core of the SCKs resulted in depression and broadening of the Tm values, which increased by ca. 5 °C when the shell was hydrated, as determined by differential scanning calorimetry measurements in the dry and 30 % (w/w) hydrated states. Passage through the melting transition was also observed for the SCKs dispersed in water, by dynamic light scattering experiments, which revealed an expansion and then collapse in hydrodynamic diameter over the temperature range of core melting. As the crystalline-amorphous core behaviors could be tuned over physiological temperature ranges, these nanoparticles are expected to be of utility as tunable drug delivery devices, with control over the kinetics and conditions of packaging and release.
壳交联类克内德尔（SCK）嵌段共聚物胶束纳米颗粒由聚（丙烯酸 - b - 丙烯酸十八酯 - 共 - 丙烯酸癸酯）制备而成，并作为具有可调核熔融转变温度（Tm）的独特体系进行了研究。通过在构建长度和化学组成相似的两亲性嵌段共聚物的疏水嵌段时，用共聚单体丙烯酸癸酯稀释丙烯酸十八酯来实现Tm降低。将这些嵌段共聚物组装成胶束并在整个壳层进行交联，从而得到了一系列SCK，其核Tm值范围为3至40°C。侧链结晶聚合物链被限制在SCK的核内导致Tm值降低和变宽，在干燥状态和30%（w/w）水合状态下通过差示扫描量热法测量可知，当壳层水合时，Tm值升高约5°C。通过动态光散射实验还观察到分散在水中的SCK经历了熔融转变，这表明在核熔融温度范围内，流体动力学直径先增大然后减小。由于结晶 - 非晶核行为可在生理温度范围内调节，预计这些纳米颗粒可作为可调药物递送装置，用于控制包装和释放的动力学及条件。
